I'm in the quest to find an insulation layer and in need of some opinions on the Campmor Polartec 200 Fleece jacket. I know this is specific to each person, but to what ballpark temperature range does this jacket keep you warm (assuming wearing underwear and base layers)? Is there a huge difference in quality and durability between the Polartec 200 and 300 fabric? There definitely is in the price ($29.99 for a 200 jacket vs $165 for a North Face Denali!) Any opinions would be appreciated!